From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Diagram of the 40/50 model's battery and magneto ignition advance curves.
| Identifier | ExFiles\Box 37\1\ scan 288 | |
| Date | 24th April 1926 guessed | |
| B D P A D P -10° 0 3° Retard IGNITION LEVER TRAVEL Advance 433 11 2/3 ° Battery Ignition Advance. Magneto Advance 40/50 BATTERY AND MAGNETO IGNITION DIAGRAM 40° 30° 23° 20° 10° 0° | ||